Developing liquid feed and vaporizing system for diazotype machines



July 21, 1959 s. K. HURLBUT 2,895,397

' DEVELOPING LIQUID FEED AND VAPORIZING SYSTEM FOR -DIAZOTYPEZ MACHINES Filed Feb. 7, 1957 2 Sheets-Sheet 1 FIGURE I GORDON K. HUR LBUT, mmvrog." (1: 4am

. ATTORNEYS July 21, 1959 u-r 2,895,397

DEVELOPING LIQUID FEED AND VAPORIZING SYSTEM 1 FOR DIAZOTYPE MACHINES Filed Feb. 7, 1957 2 Sheets-Sheet 2 FIGURE 2 GORDON K. HURLBUT, INVENTOR.

ATTORNEYS United States Patent Ofiice 2,895,397 Patented July 21, 1959 DEVELOPING LIQUID FEED AND VAPORIZING SYSTEM FOR DIAZOTYPE MACHINES Gordon K. Hurlbut, Chenango Bridge, N .Y., assignor to General Aniline & Film Corporation, New York, N.Y., a corporation of Delaware Application February 7, 1957, Serial No. 638,793

3 Claims. (Cl. 9589) This invention relates to gaseous developing apparatus and more particularly to an arrangement for the feeding of developing liquid and the vaporizing thereof.

In photocopying apparatus which utilize diazotype sensitizing -material, a gaseous medium is often used for developing the latent image. In most cases, aqueous ammonia which is vaporized in a confined enclosure is utilized for this purpose and the sensitized material is subjected to these vapors. Heretofore, the vaporizing of such developing liquid has been effected by allowing small quantities thereof to drip onto an electrical heating unit which was placed in the developing tank of the apparatus. While this type of vaporizing is satisfactory for the purpose, it was found that the expansion of the gas .in the developing tank at comparatively low pressure is subject to cooling and therefore uniform distribution is seldom obtained.

It is the primary object of this invention to obtain a more uniform vapor within the developing tank, distribution means being provided for volatilizing the liquid under pressure.

It is a particular feature of this invention that the developing liquid is gasified in a relatively small, confined, space and forcefully injected into an auxiliary chamber from which it is expelled under pressure into the developing tank of the apparatus.

Other objects and features will be apparent from the following description of the invention, pointed out in particularity in the appended claims, and taken in connection with the accompanying drawings, in which:

Fig. 1 shows a schematic layout of the liquid storage tank, the liquid feed and the vaporizing thereof; and

Fig. 2 is a cross section of a developing tank equipped with a vaporizing unit in accordance with this invention.

Referring to Fig. l, the liquid storage reservoir 4, shown here by way of example, is placed above the vaporizing chamber 5 so that the liquid 6 is fed by gravity over flexible tubular conduit 7, feed valve 8, conductor 9, drip sight glass 10 and conductor 11 to a back pressure valve 12 into the nozzle 13. The latter extends inwardly into the chamber 5 and may be supported by means of a resilient plug 14 in the vertical side wall 15 of the chamber 5. A flexible conduit 16 may be used between the nozzle 13 and the valve 12.

The chamber 5 is of an elongated tubular construction provided with a plurality of longitudinally extending, relatively narrow slits 18 through which the gasified liquid medium is forced under pressure into the developing chamber as seen in Fig. 2. A heating element 20 is placed in the chamber 5 and extends inwardly along the length thereof. The heater may be connected by the leads 21 and 22 to a suitable electrical source not shown here.

Prior to describing the operation of the vaporizing chamber, attention is directed to Fig. 2 which shows a conventional developing tank 25 having a side wall 26 which supports the vaporizing chamber 5. The front wall 28 of the tank 25 is provided with a plurality f perforations 29 which allow the gas to contact the sensitized material which is passed over the wall 28 by means of a sealing sleeve 30 riding over rollers 31 and 32. The condensate of the developing vapor is allowed to leave the tank 25 by means of the pipe 33, emptying into a Waste liquid container 34.

Referring to the operation of the vaporizing apparatus, the liquid 6, which is generally aqueous ammonia, is allowed to pass the valve 8 at a desired rate of flow determined by the opening of this valve which is controlled by the operator. The liquid frorn. the reservoir 4 flows through the pipe 9 into a drip sight glass 10 which is generally in such a position that the operator can gauge the rate of flow of the liquid. From the drip sight glass 10, the liquid is fed through the pipe 11, the

perpendicular portion of which is so dimensioned that the weight of the liquid therein be sufficient to unseat the ball 17 of the back pressure valve 12. When the ball 17 is unseated, the liquid .passes through the valve 12 into the nozzle 13 connected to the valve by means of the flexible conduit 16.

The size of the nozzle 13 is determined by the amount of developing liquid which must be distributed, and the size of the orifice of the nozzle 13 bears a relationship to the'pressure with which the liquid is to be injected into the chamber 5. In practice,,it was found that, for a rate of 40 to drops of liquid per minute in the drip sight glass 10, an orifice size of .046 inch diameter gave excellent results, the volumetric size of the orifice being about five times the diameter.

The vaporizing chamber 5 is completely sealed except for the slits 18 out along the length of the tubular housing.

The operation of the vaporizing unit is as follows. The liquid passing through from reservoir 4 lifts the ball check 17 and enters the nozzle 13. The latter absorbs heat from the heater rod 20 disposed in the chamber 5 and the liquid confined in the nozzle 13 will vaporize. The gas so produced expands rapidly and creates a considerable back pressure within the nozzle which seats the ball check 17, preventing the liquid in the nozzle 13 from returning into the feed tube. The only way out is through the nozzle orifice; thus the liquid trapped in the nozzle 13 is ejected forcibly into the vaporizing chamber 5 from which the gas leaves under pressure through the slits 18.

When the gas is expelled from the nozzle 13, the internal pressure is reduced sufiiciently so that the liquid in the conduit 11 may unseat the ball 17 allowing a fresh supply to enter the nozzle 13. The above cycle is thus repeated.

The time interval between vaporizing of the ammonia liquid in the nozzle 13 and injecting it into chamber 5 and replenishing the vaporized liquid may take from two to five seconds. It was found that a nozzle temperature producing proper cycling should be between 100 to F. Any higher heat may accelerate the gasifying process to the point of forming a gas lock at the orifice, resulting in uneven operating cycles.

As seen in Fig. 2, the chamber 5 is within the developing tank 28 so that the developing vapors expelled under pressure from the slit 18 fill the tank and maintain the vapor concentration therein at a required pressure and temeprature; thus the gas reaches the sensitized material through the perforations 29 as it is passed by means of the sealing sleeve 30. Due to the fact that developing gas is injected into the tank 28 at regular recurrent intervals, a more even distribution is maintained at a steady pressure than when the liquid is evaporated within the tank as heretofore used in such apparatus.

I claim:

1. In a developing apparatus for diazo sensitized material having a developing tank, the combination comprising a heated vaporizing chamber, said chamber having a plurality of openings therein for the passage of vapors therefrom into the tank, a liquid storage reservoir positioned at a higher elevation than said chamber, conduit means connecting said reservoir to said chamber, whereby liquid may flow from said reservoir to said chamber by gravity, said conduit means including a vertically extending portion, a nozzle extending into said chamber and tubular means for connecting said nozzle to said vertically extending portion, a fluid pressure op erated check valve in said tubular means, said check valve being arranged to open by the pressure of the head of liquid in said vertically extending portion and to close by the back pressure of the fluid in said nozzle whereby when the pressure in the nozzle exceeds the pressure of the head of liquid in said vertically extending portion, the flow of liquid from said vertically extending portion to said nozzle is cut off and when the pressure in the nozzles falls to below the pressure of the head of liquid the flow is reestablished and means in said conduit means, positioned adjacent the reservoir, to control the flow of liquid from the reservoir to the vertically extending portion.

2. An apparatus as recited in claim 1, wherein said means to control the flow of liquid from the reservoir is a valve adapted to deliver the liquid drop by drop to said vertically extending portion and wherein said conduit means is provided with a sight glass adjacent said valve on the outlet side thereof whereby the drop by drop delivery of the liquid from the valve may be observed.

3. A developing apparatus for diazo sensitized material comprising a developing tank, a vaporizing chamber 4 within the tank, said chamber having a plurality of openings in a wall thereof for the passage of vapors from the chamber into the tank, means for heating the chamber, a liquid storage reservoir positioned at a higher elevation than said chamber, conduit means connecting said reservoir to said chamber, whereby liquid may flow from said reservoir to said chamber by gravity, said conduit means including a vertically extending portion, a nozzle extending into said chamber and tubular means for connecting said nozzle to said vertically extending portion, a fluid pressure operated check valve in said tubular means, said check valve being arranged to open by the pressure of the head of liquid in said vertically extending portion and to close by the back pressure of the fluid in said nozzle whereby when the pressure in the nozzle exceeds the pressure of the head of liquid in said vertically extending portion, the flow of liquid from said vertically extending portion to said nozzle is cut off and when the pressure in the nozzle falls to below the pressure of the head of liquid the flow is reestablished and means in said conduit means, positioned adjacent the reservoir, to control the flow of liquid from the reservoir to the vertically extending portion.

References Cited in the file of this patent UNITED STATES PATENTS 2,492,781 Berggren Dec. 27, 1949 2,658,732 Holl Nov. 10, 1953 FOREIGN PATENTS 825,792 Germany Dec. 20, 1951 529,116 Canada Aug. 14, 1956 

